Effect of host age, virus dose, and route of inoculation on tumor incidence, latency, and morphology in Syrian hamsters inoculated intravenously with oncogenic DNA simian virus 40.

Three-week-old to 12-month-old male Syrian hamsters were inoculated iv with 10(8.5) median tissue culture infective dose of simian virus 40 (SV40). Three-week-old hamsters were similarly inoculated with aliquots of SV40 of progressively decreasing titers. The tumor incidence and, to a lesser extent, the tumor latency were directly dependent on the age of the animals at the time of virus exposure and on the dose of the virus. However, this age-dose dependence was not of the magnitude usually observed in hamsters inoculated with SV40 sc or im. Moreover, the wide morphologic spectrum of neoplasms induced, i.e., lymphosarcoma, reticulum cell sarcoma, and osteogenic sarcoma, by iv route of inoculation, contrasted sharply with the anaplastic and spindle-cell sarcomas which were the only types of malignant tumors resulting when other routes were used.